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August 29, 1959 an C

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Dear Yosh,

I'm sorry for the delay in answering your letter. I've been on
vacation. Thanks very much for your interest in and your comments on the
arabinose paper. first, to answer some of your queries.

I have completed the enzymatic analysis of all the mapped arabinose
mutants. However, it takes me so long to write a presentable paper that I
thought it best that the genetic and physiological experiments with intact
cells be published now, while it may be of some interest. Anyway, 1 have so
often been asked by editors to cut long papers that 1 decided to save them and
myself the trouble of re-writing.

L-arabinose induces both isomerase and kinase.
L-ribulose cannot be used by intact cells of B/r wild type or mutants.

Group C may be permease negative. 4owever, I have been unable to force
induction of either the isomerase or kinase by growing the cells in high concen-
trations of arabinose.

We have not tested for é@pimerase activity. Group © may be deficient in
the epimerase, as well as in isomerase and kinase.

As I mentioned in the footnote(5), Group 3 mutants, although all kinase
negative, have different levels of isomerase activities, varying from 1/10 to
4 times the isomerase activity of the prototroph.

J am aware of Kalckar's and Esther's work. However, since the purpose
of this paper was to describe a reliable methodology for ordering closely linked
markers and to indicate the general unreliability of Vemerec's and Hartman's
method, 1 did not think it was necessary to mention the galactose work.

As far as the tables are concerned, you must remember that we are only
interested in drawing attention to that data bearing on the order of the ara
sites in the simplest possible manner, on the basis of the reciprocal crosses.
1 think anyone reading the paragraph entitled "Urder of ara sites" on page 8
and referring to Fig. 1 and working out a few crosses with a pencil and paper
should be able to grasp the method. And then by going down lable 3 he should
be able to say that 13 is to the right of 2, 7 is to the right of 13, 4 is to
the right of 7, etc. With your notation, the apparent deduced order that we
arrive at after going over the data is given first. Jf one is to be more explicit,
it would perhaps be better to give (in Table 1) all the orders that would possibly
explain each cross, and then finally eliminate those that do not concur. By
introducing the new notation, one has to first master the meaning in terms of
threonine, arabinose 1,2,etc., leucine, and transfer this understanding to the
notation and then back again to what they represent. Also, the dots cause
confusion (as you have mentioned), being mistaken easily for decimal points.
In any case, 1 feel that employing a new system at this time would detract from
what we want to get across.

l agree with you as to the use of the + superscript, etc. The only
reason we combined data from several experiments (Table 3 and 4) 4s the unsightly
character of the table that results if we included separate figures from each
experiment.
Qe

A careful analysis of the data in Table 5, 1 believe, eliminates the
distribution of fragments as béing a major factor in the “abnormal” frequencies
we cite. Julian Gross has analyzed this problem further. You will find a portion
of this in the Carnegie Report, and he is in the process of writing a more detailed
article for publication.

49 you know of any markers between arabinose and threonine or between
arabinose and leucine? Do you know what is the enzymatic deficiency of the
arabinose negative mutant in K12 not linked to threonine or leucine’ Wo you
know of any such mutant in B/r? ~-- we have not been able to find one.

I'm disappointed that you won't be able to participate in our seminar
program. 1 was looking forward to the possibility of seeing you.

Best regards,

 

Sllis Englésberg